Polytrimethylene terephthalate is a polyester useful in fiber applications in the carpet and textile industries. The manufacture of polytrimethylene terephthalate involves the condensation polymerization of 1,3-propanediol and terephthalic acid to a polymer having an intrinsic viscosity (hereafter referred to as IV) of about 0.4 to 1.0 dl/g. The polymer melt is discharged from the melt reactor and extruded through an extrusion die into strands. The strands are quenched in cold water and cut into pellets for storage or transportation.
It has been found that polytrimethylene terephthalate pellets tend to adhere together, or block, during storage or shipping at temperatures above the polymer glass transition temperature Tg (about 45° C.), which temperature can easily be reached during storage in a silo, rail car, or hopper. Agglomeration of the pellets can also occur during drying.